Hot water-promoted cyclopropylcarbinyl rearrangement facilitates construction of homoallylic alcohols
作者:Pei-Fang Li、Cheng-Bo Yi、Jin Qu
DOI:10.1039/c5ob00305a
日期:——
H2O–1,4-dioxane and without an additional catalyst, the rearrangements of various types of cyclopropylcarbinols were attempted. It was found that the reactions generally gave homoallylic alcohols in good to very high chemical yields. Rearrangements of bicyclic or tricyclic cyclopropylcarbinols readily gave the desired ring-expanded cyclic homoallylic alcohols which are difficult to synthesize by other
A base-promoted cascade reaction of α,β-unsaturated <i>N</i>-tosylhydrazones with <i>o</i>-hydroxybenzyl alcohols: highly regioselective synthesis of <i>N-sec</i>-alkylpyrazoles
作者:Lian-Mei Chen、Juan Zhao、An-Jie Xia、Xiao-Qiang Guo、Ya Gan、Chuang Zhou、Zai-Jun Yang、Jun Yang、Tai-Ran Kang
DOI:10.1039/c9ob01780a
日期:——
N-sec-alkylpyrazoles through a base-promoted cascade cyclization/Michael addition reaction of α,β-unsaturated N-tosylhydrazones with ortho-hydroxybenzyl alcohols has been developed. The desired products containing di- or triaryl groups at the same carbon atom were afforded in good to excellent yields with excellent regioselectivities (>20 : 1). Moreover, a three-component reaction of ortho-hydroxybenzyl alcohols, α
Silver Triflate Catalyzed Cyclopropyl Carbinol Rearrangement for Benzo[<i>b</i>]oxepine and 2<i>H</i>-Chromene Synthesis
作者:Philip Wai Hong Chan、Wan Teng Teo、Shaun Wei Yong Koh、Bo Ra Lee、Benjamin James Ayers、Dik-Lung Ma、Chung-Hang Leung
DOI:10.1002/ejoc.201500374
日期:2015.7
An efficient AgOTf-catalyzed (TfO = trifluoromethanesulfonate) cyclopropyl carbinol rearrangement for the synthesis of benzo[b]oxepines and 2H-chromenes is reported by starting from 2-[cyclopropyl(hydroxy)methyl]phenols. The reactions proved to be general in scope and furnished a range of the corresponding functionalized oxygen heterocycles. The formation of the benzo-fused six-membered adduct is proposed
Catalytic Asymmetric Inverse-Electron-Demand Oxa-Diels-Alder Reaction of In Situ Generated<i>ortho</i>-Quinone Methides with 3-Methyl-2-Vinylindoles
作者:Jia-Jia Zhao、Si-Bing Sun、Sai-Huan He、Qiong Wu、Feng Shi
DOI:10.1002/anie.201500215
日期:2015.4.27
The first catalytic asymmetric inverse‐electron‐demand (IED) oxa‐Diels–Alderreaction of ortho‐quinone methides, generated in situ from ortho‐hydroxybenzyl alcohols, has been established. By selecting 3‐methyl‐2‐vinylindoles as a class of competent dienophiles, this approach provides an efficient strategy to construct an enantioenriched chroman framework with three adjacent stereogenic centers in high
AsymmetricPrinscyclization of in situ generated quinone methides and o-aminobenzaldehyde has been developed with chiral phosphoric acid as an efficient catalyst. This unconventional method provides a facile access to diverse functionalized trans-fused pyrano-/furo-tetrahydroquinoline derivatives in excellent yield and with excellent diastereo- and enantioselectivities (up to 99% yield and 99% ee)